1. Field of the Invention
The present invention relates to medical devices and, more particularly, to a strain relief system for implantable electrical stimulation leads.
2. Description of the Related Art
Spinal cord stimulation (SCS) is frequently used to treat patients with chronic neuropathic pain who have not found relief using other treatments. In general, neurostimulation works by applying an electrical current to the nerves located near the source of chronic pain. More particularly, a thin wire with an electrical lead at one end is implanted into a patient in the location to be treated, such as a particular portion of the spine. An electrical generator connected to the wire is used to deliver electrical current to the lead, thereby stimulating the nerves at the treatment location.
Although spinal cord stimulation may produce dramatic results for patient pain care, the systems used to supply the electrical stimulation to the spine are subject to failure and may lead to reduced effectiveness or require additional surgery to correct or replace the defective portions of the system. The most common complications associated with spinal cord stimulation fall into two general categories. The first category of problems that affects spinal cord stimulation systems is the migration of the electrodes away from the intended targets. This complication may occur in over ten percent of patients receiving spinal cord stimulation. The second category of problems that affects spinal cord stimulation systems is the breakage of the electrical leads. This complication may occur in nearly ten percent of patients receiving spinal cord stimulation. As a result of these complications, the spinal cord stimulation system may need to be repaired or replaced, if possible, through additional patient surgical procedures. Thus, the risks to the patient of more serious complications and the overall costs associated with obtaining neurostimulation treatment are increased.
Convention methods for affixing stimulation leads in place include suture sleeves having elastomeric gripping portions positioned therein. When the suture sleeve is sutured into position along the spinal column, the gripping sleeve is compressed around the pacing lead, thereby enhancing retention of the lead. While such systems may limit lead migration, they do not limit the stresses that cause fracturing or breaking of the lead wires. Conventional methods for reducing fracturing involve the use of strain relief members that extend from the lead anchors. Unfortunately, these strain relief members simply relocate stress points and thus fail to reduce the occurrence of fractures.